Although equipment which is capable of recording or transmitting regular, relatively low resolution video standard signals (PAL or NTSC for example) is common and inexpensive, equipment capable of recording or transmitting the higher resolution images typically associated with computer workstations is not readily available or is prohibitively expensive.
Others have sought to store or transmit high resolution pictures as a series of lower resolution pictures, with varying degrees of success. Goldberger, U.S. Pat. No. 3,803,352, discloses converting a high resolution video image for storage on low-resolution magnetic tape but is limited to handling only still images that are an integral multiple of the number of lines in the storage medium. Goldberger cannot handle lines that have more horizontal detail than NTSC and Goldberger makes no provision for dividing lines into horizontally adjacent segments. Arlan et al., U.S. Pat. No. 4,660,096, disclose storing portions of a high resolution video image in low resolution for storage on conventional media. This system also is limited to still images only and can only provide integral reductions. Hailey et at., U.S. Pat. No. 4,991,010, disclose an interpolation filter for simply reducing the resolution of a complete high resolution image to a lower resolution.